Sheet processing apparatus and image forming apparatus

ABSTRACT

When a sheet bundle formed on a processing tray descends in a sheet bundle conveying path by a sheet bundle conveying mechanism while a front edge of the sheet bundle is nipped, a band sheet is circled to a front edge side and overlaid to front and back surfaces. The band sheet is perforated at a plurality of positions by a cutter and, thereafter, cut to a necessary length. Both edges of the band sheet are stapled integratedly with the sheet bundle by a stapler main body also serving as a stapling of the sheet bundle. If the band sheet is not torn at the perforation, its contents cannot be browsed. Therefore, security holding performance of the sheet bundle is raised.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a sheet processing apparatus for overlaying sheets and executing a binding process and, more particularly, to the binding process for holding security of a sheet bundle.

2. Description of the Related Art

Hitherto, a sheet processing apparatus in which after a sheet bundle was formed by overlaying image-formed sheets, one side of the sheet bundle is stapled has been put into practical use. A sheet processing apparatus in which various types of printed matter are paper-banding processed by using a band in which an adhesive layer such as a heat seal or the like has been formed in an edge portion has also been put into practical use. A sheet processing apparatus in which sheets on which examination questions or the like have been printed are bundle-folded and booklet-bound, thereby giving security holding performance to inside pages of a brochure has also been put into practical use.

Several techniques for giving the security holding performance to the inside pages of a sheet bundle by using a stapling apparatus which is equipped as a standard for the sheet processing apparatus and which staples one side of the sheet bundle at a plurality of positions to thereby obtain a booklet shape have also been proposed.

For example, in Japanese Patent Application Laid-Open No. H09-071362, a sheet processing apparatus in which after a sheet bundle was formed by overlaying image-formed sheets, the sheet bundle is folded by setting an image forming surface to the inside, and an open end of the folded bundle is stapling processed has been shown.

In Japanese Patent Application Laid-Open No. H09-165136, a sheet processing apparatus in which a long security holding sheet is overlaid to the side of one side of a sheet bundle by winding the sheet bundle and an edge portion on the side of one side is stapled also by serving as a bundle-stapling of the sheet bundle has been shown. Such a technique that perforations are formed in both of the security holding sheet and the sheets in order to enable the security holding of the sheet bundle to be easily cancelled has been disclosed.

Further, in Japanese Patent Application Laid-Open No. H07-001890, a sheet processing apparatus in which a band whose length is longer than that of one round of a sheet bundle is wound around the sheet bundle in association with a movement of the sheet bundle so as to obtain an envelope shape has been shown.

In the security holding process shown in Japanese Patent Application Laid-Open No. H09-071362, it is necessary to remove the stapling when the security holding of the sheet bundle is cancelled. A special tool is necessary to remove the stapling. A long working time including a preparation and an experience and a skill are necessary. After the stapling was removed, holes as stapling traces remain. Since the sheet bundle is separated into the sheets simultaneously with the cancellation of the security holding, a possibility that the sheet on which the security information has been printed is scattered and lost or page order is disordered occurs.

In the security holding process shown in Japanese Patent Application Laid-Open No. H09-165136, since the sheet bundle which has separately been formed is sandwiched to the inside of the large folio security holding sheet and the stapling is executed, a large mechanism space and a mechanism of a large scale are necessary. Since the sheet bundle is hidden inside of the large security holding sheet which has been folded into halves, the stapling cannot be performed to accurate positions of the edge portion on the side of one side of the sheet bundle at the time of the stapling process.

Since the security holding sheet of a regular size is used, if a thickness of sheet bundle increases and a length of security holding sheet becomes relatively insufficient, the stapling cannot be performed to the predetermined positions of the sheet bundle. If the stapling positions are shifted to the center side of the sheet bundle according to the length of security holding sheet, the stapling positions overlap the printed portion of the sheet and the contents printed in a brochure state cannot be read. A mechanism and control for detecting the edge portion of the security holding sheet and shifting the stapling positions to the center side of the sheet bundle are necessary. It is difficult to assemble such mechanism and control as an additional function into the existing sheet processing apparatus.

In the case where a long security holding sheet is used from the beginning by assuming a thick sheet bundle, the security holding sheet is stapled to a thin sheet bundle in a state where an edge of the security holding sheet is largely projected from an edge portion on the side of one side of the thin sheet bundle. Thus, an outward appearance and handling performance (stacking performance) deteriorate. In order to trim the projected edge of the security holding sheet after the stapling was performed, there is not any method than cutting the security holding sheet together with the sheet bundle. However, it is impossible to assemble a cutting mechanism as an additional function into the existing sheet processing apparatus.

In the process for enclosing the sheet bundle into the envelope disclosed in Japanese Patent Application Laid-Open No. H07-001890, it is necessary to prepare an envelope material sheet which has been cut according to the sheet size and thickness of the sheet bundle to be handled. Such drawbacks that if the envelope material sheet is shorter than the sheet bundle, the envelope cannot be formed and that if the envelope material sheet is too longer than the sheet bundle, a flap is widened and an outward appearance of a completion state (envelope) deteriorates are similar to those mentioned in Japanese Patent Application Laid-Open No. H09-165136.

SUMMARY OF THE INVENTION

The invention provides a sheet processing apparatus in which a security holding process which provides a good outward appearance can be realized by a simple mechanism arranged in a small space.

According to the invention, there is provided a sheet processing apparatus comprising: a tying member supplying portion which supplies a tying member, the tying member is wound around a sheet bundle formed by a plurality of sheets and ties the sheet bundle; a binding unit which binds the sheet bundle integratedly with the tying member wound around the sheet bundle; and a control portion which changes a length of the tying member to be supplied by the tying member supplying portion according to a thickness of the sheet bundle.

According to the sheet processing apparatus of the invention, the tying member supplying portion supplies the tying member of the length according to the thickness of the sheet bundle. In other words, the tying member supplying portion supplies the tying member of the proper length which provides the good outward appearance in a state where it has been security holding processes integratedly with the sheet bundle. Thus, when the winding portion winds the tying member to the other side on the side opposite to one side and overlays both ends of the tying member to a front and back surfaces of an edge portion on the side of one side of the sheet bundle, the edge portion of the tying member can be accurately positioned to the edge portion on the side of one side. Irrespective of the thickness of sheet bundle, the binding unit can bind the sheet bundle and the edge portion of the tying member so as to provide the good outward appearance at a predetermined position of the inside of one side which has been set.

Therefore, even if the mechanism to move the binding unit to the center side of the sheet bundle according to a change in position of the edge portion of the tying member and the mechanism to integratedly trim the tying member and the sheet bundle after the binding process do not exist, the security holding process which provides the good outward appearance can be realized. The security holding process which provides the good outward appearance can be realized by a simple mechanism arranged in a small mechanism space.

Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are explanatory diagrams of a construction of an image forming apparatus having a sheet processing apparatus.

FIG. 2 is an explanatory diagram of a construction of the sheet processing apparatus.

FIGS. 3A, 3B and 3C are explanatory diagrams of the buffer operation.

FIGS. 4A, 4B, 4C and 4D are explanatory diagrams of the nipping operation of a sheet bundle.

FIGS. 5A, 5B and 5C are explanatory diagrams of the conveying operation of a band sheet.

FIG. 6 is an explanatory diagram of a band sheet cutting blade.

FIGS. 7A and 7B are explanatory diagrams of the band sheet tying operation.

FIG. 8 is a flowchart for control of the sheet processing apparatus.

FIGS. 9A and 9B are explanatory diagrams of another embodiment of a security holding process.

DESCRIPTION OF THE EMBODIMENTS

An image forming apparatus according to an embodiment of the invention will be described in detail hereinbelow with reference to the drawings. The sheet processing apparatus of the invention is not limited to a construction of the embodiment which will be described hereinbelow. So long as a sheet bundle is security-held by using a fixed tying member also serving as a binding process of a sheet bundle, the invention can be also embodied by another embodiment in which a part or all of the construction of the embodiment is replaced by its alternative construction.

In the embodiment, an independent sheet processing apparatus arranged on a downstream side of an apparatus main body which forms an image will be described. The sheet processing apparatus of the invention can be built in a casing of each of various devices arranged on an upstream side and control of the sheet processing apparatus can be also made by a control device of the upstream side device or by an independent external control device.

In the embodiment, the image forming apparatus which forms a full color image by overlaying and transferring toner images of respective separation colors onto a sheet will be described. The image forming apparatus of the invention is not limited to an image forming apparatus of an electrophotographic system but any one of various printing systems such as ink jet system, thermal transfer system, and the like can be used. The invention can be embodied according to various applications such as printing apparatus, copying apparatus, printer, facsimile apparatus, multifunction printer (MFP), and the like.

(Image Forming Apparatus)

FIGS. 1A and 1B are explanatory diagrams of a construction of the image forming apparatus having the sheet processing apparatus. FIG. 1A is an overall view and FIG. 1B is a block diagram.

As illustrated in FIG. 1A, in an image forming apparatus 10, a sheet processing apparatus 200 as an independent option apparatus is connected to a downstream side of an apparatus main body 100 to form images onto sheets S. The apparatus main body 100 has image forming portions 105, 106, 107, and 108 provided as common units. The image forming portions 105, 106, 107, and 108 have developing devices which are filled with toner of four different colors of yellow, cyan, magenta, and black. The sheets S which are used for image creation are taken out one by one from sheet cassettes 101, 102, 103, and 104 corresponding to different sheet sizes. The extracted sheet is adsorbed and held onto a transfer belt 120 and conveyed.

The image forming portions 105, 106, 107, and 108 form toner images of yellow, cyan, magenta, and black by the electrophotographic system, and the toner images are transferred onto the sheet S on the transfer belt 120 and overlaid. The sheet S on which the toner images of four layers have been overlaid and held is conveyed to a fixing device 110 and heated and pressed. Thus, the toner images are fixed onto a surface of the sheet and a full color image is formed. The sheet S formed with the full color image is discharged to the sheet processing apparatus 200.

The sheet processing apparatus 200 stacks the sheets S received one by one from the apparatus main body 100 onto a processing tray 213, thereby forming a sheet bundle St. The sheet bundle St formed on the processing tray 213 is conveyed to a sheet bundle conveying path 294 and an edge of a rear edge side of the sheet bundle St is subjected to a stapling process by a stapler main body 240. A staple receiving portion 241 serving as a binding unit. The stapling processed sheet bundle St is put onto a bundle discharging belt 250 and discharged onto a lower discharged sheet stacking plate 261.

As illustrated in FIG. 1B, the apparatus main body 100 has an operation input portion 151 for making various settings and operation instructions through a touch panel in an interactive manner. A control portion 150 controls each portion of the apparatus main body 100 according to the various settings and operation instructions which have been input through the operation input portion 151.

In the embodiment, the sheet processing apparatus 200 has an independent control portion 160 different from the control portion 150 of the apparatus main body 100. The control portion 160 controls electric parts 170 such as motor, sensor, solenoid, clutch, and the like and makes a mechanism 180 such as roller, belt, switching member, or the like operative. It is also possible to provide the control portion 160 integratedly with the control portion 150 of the apparatus main body 100 and to directly control the sheet processing apparatus 200 from the apparatus main body 100 side.

(Sheet Processing Apparatus)

FIG. 2 is an explanatory diagram of a construction of the sheet processing apparatus. FIGS. 3A to 3C are explanatory diagrams of the buffer operation. FIGS. 4A to 4D are explanatory diagrams of the grasping operation of a sheet bundle. FIGS. 5A to 5C are explanatory diagrams of the conveying operation of a band sheet. FIG. 6 is an explanatory diagram of a band sheet cutting blade. FIGS. 7A and 7B are explanatory diagrams of the band sheet tying operation.

As illustrated in FIG. 2, the sheets S are sequentially fed from an inlet roller 201 to conveying rollers 202 and 203 and a buffer conveying roller 204 and guided to a conveyance switching member 211. The conveyance switching member 211 switches a conveying path 292 which is used when the sheet bundle St is formed and an upper discharging path 293 which is used when the sheets S are discharged and stacked as they are without forming the sheet bundle St. The sheet S conveyed to the upper discharging path 293 pass through an upper sheet discharging roller 208 from an upper conveying roller 207 and is discharged onto an upper discharged sheet stacking plate 260 which can be elevated up and down.

By switching the conveyance switching member 211 to the conveying path 292, the sheet S is received from the buffer conveying roller 204, sent to a lower sheet discharging roller 206, and is discharged onto the processing tray (bundle forming portion) 213. When the sheets S are stacked onto the processing tray 213 and the sheet bundle St is formed, the sheet bundle St is conveyed to the sheet bundle conveying path 294 and processes of the sheet bundle St is started. The subsequent sheets S cannot be received to the processing tray 213 until the completion of the processes of the sheet bundle St. Therefore, during such a period of time, a plurality of subsequent sheets S are overlaid and set into a waiting mode on a buffer path 291, thereby assuring a processing time of the precedent sheet bundle St (hereinafter, such an operation is referred to as a buffer operation).

As illustrated in FIG. 3A, a conveyed first sheet S1 is conveyed in the direction shown by an arrow A by the buffer conveying roller 204 and stopped on the conveying path 292 in a state where a rear edge of the sheet S1 is not passed through the buffer conveying roller 204.

Subsequently, as illustrated in FIG. 3B, a buffer switching member 210 is switched to the direction shown by an arrow C. After that, the sheet S1 is conveyed in the direction shown by an arrow B so as to be returned to the buffer path 291. The sheet S1 is stopped near the position where the rear edge of the sheet S1 (front edge of the sheet S1 before the conveying direction is switched) has been passed through the buffer switching member 210.

Subsequently, as illustrated in FIG. 3C, the buffer switching member 210 is switched to the direction shown by an arrow D. The sheet S1 in the buffer path 291 is conveyed to the direction shown by an arrow E at timing matched with a sheet S2 which has subsequently been sent. By changing the timing to start the conveyance of the sheet S1 to the direction of the arrow E, an amount of deviation occurring when the sheet S1 is overlaid to the sheet S2 can be arbitrarily changed.

The sheet S2 conveyed in the direction of the arrow D is overlaid to the sheet S1 at a position near the buffer switching member 210, conveyed to the conveying path 292 in the overlapped state, and stopped in the state where a rear edge is not passed through the buffer conveying roller 204.

After that, by repeating the operations of FIGS. 3A to 3C, the increased number (for example, 3 or 4) of sheets can be also overlaid onto the conveying path 292. As illustrated in FIG. 2, the sheets S1 and S2 held on the conveying path 292 in the waiting mode are received onto the lower sheet discharging roller 206 after waiting for the state where the processing tray 213 can receive the sheets. Those sheets are discharged onto the processing tray 213 in the overlapping state.

The subsequent sheets S which are not buffer-processed are successively discharged one by one onto the sheets S1 and S2 stacked on the processing tray 213. Each time the sheets S1, S2, and S are discharged onto the processing tray 213, their front edges collide with a front edge reference plate 214 and are aligned. Each time the sheets S1, S2, and S are discharged onto the processing tray 213, they are pushed up to a width of each of the sheets S1, S2, and S in the direction perpendicular to the sheet surface and their side edges are aligned by a pair of side edge aligning plates (not shown). The stacking and aligning operations of the sheets S are repeated until the sheets of the number as many as the number of sheets adapted to form one brochure are stacked onto the processing tray 213, so that the sheet bundle St is formed.

As illustrated in FIG. 2, when the sheet bundle St is formed onto the processing tray 213, a sheet bundle conveying mechanism 220 is moved in the thickness direction of the sheet bundle St and grasps the front edge side of the sheet bundle St. The sheet bundle conveying mechanisms 220 are arranged at three positions in the width direction of the sheet bundle St where they do not interfere with the stapler main body 240 and the staple receiving portion 241 upon elevation. In the thickness direction of the sheet bundle St, the sheet bundle St is moved between the grasping position and the releasing position of the sheet bundle St. In the state where the sheet bundle St has been grasped, the sheet bundle conveying mechanism 220 is elevated up and down along the sheet bundle conveying path 294 and positions the stapling position of the sheet bundle St to the stapler main body 240 (binding unit).

The front edge reference plate 214 is a restricting member serving as an alignment reference in the conveying direction of the sheets S1, S2, and S discharged onto the processing tray 213. The front edge reference plate 214 is attached to a front edge reference base plate 216 so as to be rotatable in the directions shown by arrows G by a rotary axis 215. The front edge reference base plate 216 is movable in the directions shown by arrows F in the state where the front edge reference plate 214 has been held so as to cope with the sheets S of a different size.

A band sheet (tying member) Bs is provided as consumables only for use of the security holding process obtained by winding a strong paper material (tying material) having a width of 30 mm into a roll shape. A plurality of band sheets Bs are arranged at the stapling (binding) positions of the stapler main body 240 and enclosed in an apparatus body of the sheet processing apparatus 200. In the case of executing the security holding process, the band sheet Bs penetrates the sheet bundle conveying path 294 in the thickness direction and its one end is grasped by a band pressing member 234.

While the sheet bundle St grasped by the sheet bundle conveying mechanism 220 descends on the sheet bundle conveying path 294, it does not interfere with the sheet bundle conveying mechanism 220 but the sheets are sequentially pulled out of the roll, wound at a lower edge of the sheet bundle St, and overlaid onto the front and back surfaces of the sheet bundle St.

A cutter (cutting portion, perforation processing portion) 235 is controlled by the control portion (160 in FIG. 1B) of the sheet processing apparatus 200 and cuts the band sheet Bs to a necessary length. In the control portion 160, a size and a material of the sheets and the number of stacked sheets are designated from the control portion (150 in FIG. 1B) of the apparatus main body 100 side. The necessary length of the band sheet Bs is a length starting with an edge portion on the side of one side of the front surface of the sheet bundle St, winding around the other side on the opposite side, and reaching an edge portion on the side of one side of the back surface. That is, the necessary length is a length obtained by adding a thickness of sheet bundle St to a value which is twice as long as the length in the conveying direction of the sheet bundle St. The cutter 235 also functions as a perforation processor for forming perforations at a plurality of positions (specific positions) in the longitudinal direction of the band sheet Bs.

As illustrated in FIG. 4A, the sheet bundle conveying mechanism 220 moves a grasping portion 221 in the direction shown by an arrow H in the diagram so as to grasp the sheet bundle St, thereby allowing the sheet bundle St to be grasped between the grasping portion 221 and a grasping portion 222. FIG. 4B illustrates a state where the sheet bundle St has been grasped by the sheet bundle conveying mechanism 220.

Although it has been disclosed in FIG. 4A that only the grasping portion 221 is moved, both of the grasping portion 221 and the grasping portion 222 can be also moved. It is also possible to fix the grasping portion 221 and move the grasping portion 222. In the sheet bundle conveying mechanism 220, in order to prevent a deviation from the sheet bundle St, there is a case where a pad made of a rubber material, a cloth, or the like as a base material is used as a sheet contact surface of each of the grasping portions 221 and 222 or there is a case where the sheet contact surface has a rough surface shape.

After the sheet bundle St was grasped by the sheet bundle conveying mechanism 220, as illustrated in FIG. 4C, the front edge reference plate 214 rotates in the directions of the arrows G so as to enable the sheet bundle St to be conveyed to the downstream. A protection guide 223 is a member which is located between the band sheet Bs and the sheet bundle St and protects the front edge of the sheet bundle St. The protection guide 223 is arranged at a position where it does not interfere with the front edge reference plate 214 in correspondence to the band sheet Bs.

After that, as illustrated in FIG. 4D, while grasping the sheet bundle St, the sheet bundle conveying mechanism 220 moves in the direction of an arrow I, thereby conveying the sheet bundle St to the downstream.

As illustrated in FIG. 5A, in the initial state, in the state where the band sheet Bs had been cut by the cutter 235 at the previous time, the front edge side of the band sheet Bs has been nipped by a conveying roller 230 (tying member supplying portion) and stopped. The cutter 235 executes the perforating process and the cutting process to the band sheet Bs which was pulled out of the roll and conveyed by the conveying roller 230.

As illustrated in FIG. 6, an edge of a blade of the cutter 235 has a shape having concave and convex portions like sawteeth. By controlling a penetration amount of the cutter 235, the perforating process and the cutting process are switched. The blade edge of the cutter 235 has concave portions 239 and convex portions 238. When only the convex portions 238 are penetrated into the band sheet (Bs in FIG. 2), the perforating process is executed. When both the convex portions 238 and the concave portions 239 are penetrated, the cutting process is executed.

A band sheet receiving base plate (not shown) is arranged so as to face the blade edge of the cutter 235. The penetration amount of the cutter 235 is adjusted by a method whereby a biting amount of the band sheet receiving base plate of the cutter 235 is switched into two stages by an abutting mechanism (not shown). As illustrated in FIG. 7B, the band sheet Bs has been perforation processed so that a perforation Mm is located at the center on the surface of the sheet bundle St.

A mode in which the perforation process is not executed or the like can be also selected according to a setting level of the security holding process. Those processes differ depending on a type of final sheet bundle which is required.

As illustrated in FIG. 5B, in association with the conveyance of the band sheet Bs by the conveying roller 230, a receiving and handing guide 236 rotates in the direction shown by an arrow L around a rotary axis 237 as a rotational center and stands in the sheet bundle conveying path 294. The front edge of the band sheet Bs is guided onto an upper surface of the receiving and handing guide 236 which is standing, penetrates the sheet bundle conveying path 294, transverses, and is handed to the opposite band pressing member 234. When the front edge of the band sheet Bs reaches the band pressing member 234, the band pressing member 234 nips the front edge of the band sheet Bs as illustrated in FIG. 5C. The receiving and handing guide 236 rotates again, is returned to the original position, retreats from the sheet bundle conveying path 294, and does not obstruct the descent of the sheet bundle (St in FIG. 2). In the step of pulling out band sheet Bs from the roll, the cutter 235 is moved in the directions shown by arrows K and the perforation process is executed.

A decurling roller pair (231, 232) contributes to the conveyance of the band sheet Bs together with the conveying roller 230. To eliminate a curling property of the band sheet Bs wound in a roll shape, the upper decurling roller 231 is made of a foaming material or the like whose hardness is smaller than that of the lower decurling roller 232. The lower decurling roller 232 bites a peripheral surface of the upper decurling roller, so that a nip is formed. When the band sheet Bs passes through the nip, the curling property is corrected.

Although the mechanism for correcting the curling property by using the decurling pair (231, 232) has been used in the embodiment, its correcting method is not limited but there is no problem even if any one of a mechanism using a belt and a roller, a mechanism using three or more rollers, and the like is used.

As illustrated in FIG. 7A, in association with the descent of the sheet bundle conveying mechanism 220 (winding portion), the band sheet Bs is automatically wound around the front edge side of the sheet bundle St and overlaid to the front and back surfaces of the sheet bundle St.

In the state where the band sheet Bs penetrates the sheet bundle conveying path 294 and is arranged, the sheet bundle St grasped by the sheet bundle conveying mechanisms 220 is conveyed along the sheet bundle conveying path 294. The band sheet Bs is gradually pressed downward by the front edge side of the sheet bundle St and is gradually pulled out of the roll.

When the front edge portion of the sheet bundle St is directly come into contact with the band sheet Bs, if the number of sheets of the sheet bundle St is small or each sheet S is thin paper, there is a possibility that a peel-off of the edge portion of the sheet bundle St, wrinkles, a hitting trace, or the like occurs by a frictional contact with the band sheet Bs.

To prevent such a problem, the protection guide 223 which can be inserted and projected is provided for the sheet bundle conveying mechanism 220 in order to protect the front edge in the progressing direction of the sheet bundle St. The protection guide 223 has a length as long as a width of band sheet Bs and is arranged at a position corresponding to the band sheet Bs. The protection guide 223 can be inserted and ejected in such a manner that it is moved in the width direction of the band sheet Bs and is retreated from a gap between the sheet bundle St and the band sheet Bs.

Prior to starting to descend, the protection guide 223 is set in a position of the sheet bundle St which faces the band sheet Bs. The sheet bundle St reaches the position where the band sheet Bs is in the waiting mode while setting the protection guide 223 to a head (FIG. 4D, FIG. 7A). After that, the band sheet Bs is fed and the sheet bundle St is conveyed by the sheet bundle conveying mechanism 220. The front edge in the conveying direction of the sheet bundle St is set to a vertex portion and the band sheet Bs is pushed, bent, and wound around the sheet bundle St.

The cutting of the band sheet Bs is executed by the cutter 235 at timing when the conveyance of the length necessary for the security holding process has been completed. At the same time, the nipping of the front edge portion of the band sheet Bs by the band pressing member 234 is cancelled. Thus, a state where the band sheet Bs has been wound as one sheet around the front and back surfaces of the sheet bundle St is obtained. The protection guide 223 is retreated from the gap between the sheet bundle St and the band sheet Bs.

After that, a pressing roller 242 presses and overlays the band sheet Bs onto the surface of the sheet bundle St, applies a predetermined braking load to the band sheet Bs and the sheet bundle St, and eliminates a looseness of the band sheet Bs. Thus, such a situation that the looseness of the band sheet Bs occurs in the sheet bundle conveying path 294 or an adhesion is deteriorated is prevented.

As for the sheet bundle St conveyed by the sheet bundle conveying mechanism 220, its one side is positioned to the stapler main body 240 (binding unit) as illustrated in FIG. 7B. The binding process also serving as a security holding process is executed by both of the stapler main body 240 and the staple receiving portion 241. The stapler main body 240 ejects staples toward the staple receiving portion 241, allows the staples to penetrate the edge portion of the overlap of the band sheet Bs and the sheet bundle St, and allows the front edges of the staples to collide with the staple receiving portion 241 so as to be bent inwardly. Thus, in the stapler main body 240 and the staple receiving portion 241, both edge portions of the band sheet Bs are fixedly bound around the sheet bundle St.

Although both edges of the band sheet Bs are projected from the edge portion on the side of one side of the sheet bundle St in FIG. 7B, actually, the cutting length of the band sheet Bs is controlled as mentioned above, thereby allowing those both edges to coincide with the edge portion on the side of one side of the sheet bundle St.

The timing for retreating the protection guide 223 can be also set to the timing before or after the binding operation which is executed by the stapler main body 240 and the staple receiving portion 241. When the processes of the next sheet bundle are executed, the protection guide 223 has been moved to an original position where the edge portion of the sheet bundle St can be protected.

As illustrated in FIG. 7A, after the binding operation, the sheet bundle conveying mechanism 220 further descends and conveys the sheet bundle St, thereafter, cancels the restraint of the sheet bundle St, thereby sending the sheet bundle St to the bundle discharging belt 250. The bundle discharging belt 250 conveys the sheet bundle St and discharges it onto the lower discharged sheet stacking plate 261.

(Control of Sheet Processing Apparatus)

FIG. 8 is a flowchart for control of the sheet processing apparatus. FIG. 8 describes the foregoing security holding process as a process of the control portion 160 illustrated in FIG. 1B.

As illustrated in FIG. 8, when job contents are transmitted from the control portion 150 of the apparatus main body 100, the control portion 160 of the sheet processing apparatus 200 discriminates whether or not the security holding process (tying process) is executed (S11).

If the tying process is designated (YES in S11), the control portion 160 allows the sheets to be stacked onto the processing tray 213 and forms the sheet bundle St (S12). When the sheet bundle St is formed, the control portion 160 allows the front edge of the sheet bundle St to be nipped by the sheet bundle conveying mechanism 220 (S13). The control portion 160 allows the sheet bundle St to descend in the sheet bundle conveying path 294 by the sheet bundle conveying mechanism 220 (S14).

In parallel with the control in S12 to S14, the control portion 160 starts to supply the band sheet Bs by the conveying roller 230 and the decurling roller pair (231, 232) (S21). The control portion 160 discriminates whether or not the perforating process has been designated (S22). If the perforating process has been designated (YES in S22), the perforating process is executed by the cutter 235 (S23). If it is not designated, the band sheet Bs is cut by the cutter 235 at a predetermined descending position of the sheet bundle St and the band sheet Bs is in the waiting mode at the initial position (S24).

When the sheet bundle St is positioned to the stapler main body 240 by the sheet bundle conveying mechanism 220, the tying is completed (S15). The control portion 160 discriminates whether or not the binding process has been designated (S16). If the binding process has been designated (YES in S16), the control portion 160 retreats the protection guide 223 (S17) and makes the stapler main body 240 operative (S18).

If the security holding process (tying process) has been designated (YES in S11), the binding process has certainly been designated. Even if the tying process is not designated (NO in S11), when the binding process has been designated (YES in S16), the control portion 160 retreats the protection guide 223 (S17) and makes the stapler main body 240 operative (S18). When the binding process is completed (S18), the control portion 160 releases the sheet bundle conveying mechanism 220, sends the sheet bundle St onto the bundle discharging belt 250, and discharges it onto the lower discharged sheet stacking plate 261 (S19).

If the binding process is not designated (NO in S16), the control portion 160 releases the sheet bundle conveying mechanism 220 without making the stapler main body 240 operative and sends the sheet bundle St onto the bundle discharging belt 250 (S19).

(Modification of Security Holding Process)

The form of the sheet bundle obtained after the security holding process is not limited to the form illustrated in FIG. 7B. FIG. 9A is an explanatory diagram of another form of the security holding process. FIG. 9B is an explanatory diagram of another form of the perforating positions.

In the form illustrated in FIG. 9A, the security holding process is executed to the sheet bundle St by using the band sheet Bs of a wide width which stretches over two stapling (binding) positions Sp. A width of band sheet Bs is set to be shorter than a width of sheet bundle so that a grasping margin of the sheet bundle conveying mechanism is assured to the outsides of the stapling positions Sp (the sheet bundle is not grasped in an intermediate portion between the stapling positions Sp).

By writing a destination address onto the band sheet Bs and adhering a stamp thereon, the sheet bundle can be mailed as an opened book. The perforations Mm are formed at positions near the stapling positions Sp of the front and back surfaces of the sheet bundle St and at a position on the front edge side. Therefore, when the band sheet Bs is torn at the perforations Mm, the portions of the band sheet Bs remaining on the sheet bundle St reinforce the stapling positions Sp and a looseness of the sheet bundle St and a falling of the sheet can be prevented. When the sheets are thin or weak, the stapling (binding) portions can be reinforced.

Either a mode to supply the band every stapling position (binding position) or a mode to supply the band of the wide width which stretches over the two stapling positions is selectively determined according to a security level by preparing a plurality of rolls having different widths. The invention is also effective in the case of executing the security holding process in which the band sheet stretches over the three or more stapling positions. When there are a plurality of stapling positions, it is also possible to classify the stapling positions into several groups and to supply the band every group.

FIG. 9B shows the form corresponding to FIG. 7B and is the explanatory diagram in the case where the perforating positions are made different. The invention is also effective in the case of executing the security holding process at each of the three or more stapling positions. The perforations Mm have been formed at the positions near the stapling positions Sp of the front and back surfaces of the sheet bundle St. Therefore, after the band sheet was torn at the perforations Mm and the security holding was cancelled, the remaining band sheet becomes the reinforcement portions of the stapling portions as mentioned above.

Although the security holding process has been added to the sheet processing apparatus which can form the bundle and execute the binding process in the embodiment, the invention can be also embodied as a dedicated security holding processing apparatus. The invention can be also embodied as a form in which the bundle forming mechanism is not built in but the security holding process is executed to the sheet bundle conveyed from another apparatus on the upstream side.

Although the band sheet Bs has been provided in a roll shape into the apparatus body in the embodiment, the band sheet Bs can be also provided in the apparatus body by a method whereby band sheets which have been cut and aligned from the beginning so as to have a predetermined length and perforated at predetermined positions are enclosed in the cassette in a stacked state. In such a case, it is also possible to construct in such a manner that the band sheet having a slightly long length is prepared and after the length is adjusted according to the sheet size and thickness of the sheet bundle St, the band sheet is overlaid to the front and back surfaces of the sheet bundle St and the binding process is executed.

Although the protection guide 223 has been descended integratedly with the sheet bundle conveying mechanism 220 in the embodiment, it is also possible to descend the protection guide 223 prior to the sheet bundle conveying mechanism 220 and to bend the band sheet Bs into a shape which conforms with an external appearance of the sheet bundle St. In such a case, it is also possible to construct in such a manner that after the protection guide 223 was retreated, by falling down the sheet bundle conveying mechanism 220, the sheet bundle St and the band sheet Bs are overlaid.

In the embodiment, in the state where the front edge of the band sheet Bs has been fixed to one side of the sheet bundle conveying path 294, the band sheet Bs is pushed down by the protection guide 223 and the band sheet Bs is sequentially pulled out from the opposite side of the sheet bundle conveying path 294. It is also possible to construct in such a manner that the center position of the band sheet Bs in the longitudinal direction is set under the protection guide 223, the band sheet is cut to a necessary length, and by falling down the sheet bundle St without restricting both edges of the band sheet Bs, the sheet bundle St can be overlaid to the band sheet Bs in the folio state. In such a case, although an extra waiting space of the band sheet Bs is necessary, the friction of the band sheet Bs against the front edge of the sheet bundle St is slightly reduced.

As mentioned above, in the embodiment, when the sheet bundle St is bound by a binding device such as a stapler or the like, the roll-shaped band sheet Bs having the side shorter than one side of the sheet bundle St to be bound is supplied as a band adapted to wrap the sheet bundle St therein. Since the band sheet Bs is banded so as to enclose the sheet bundle St and fastened by the binding unit together with the sheet bundle St, although the sheet bundle St has been bound, by tearing the band sheet Bs, the print information can be easily browsed. By using a mechanism for making a perforation or the like to an arbitrary position of the band sheet Bs which is supplied or by using a perforated band sheet, the security of the sheet bundle St can be easily cancelled by tearing the band sheet Bs.

Since the width of band sheet Bs is shorter than the length of one side of the sheet bundle St, necessary information and information which has to be displayed can be clearly shown to the user while satisfying the security function of the sheet bundle St. Since the edge portion of the sheet bundle St is open, a defect such as a missing of the sheet or the like in the sheet bundle St can be also directly inspected.

On the other hand, according to the security holding processes disclosed in Japanese Patent Application Laid-Open Nos. H09-165136 and H07-001890, since the whole width of the sheet bundle is covered with the security holding sheet or envelope, it is difficult to confirm the missing of the sheet or disorder of the sheet bundle or print contents of a front sheet portion. As disclosed in Japanese Patent Application Laid-Open No. H09-165136, if perforations to cancel the security holding are formed in all pages of the sheet bundle, the cutting portion from the perforations narrows a printable area of the sheet bundle.

Since the band sheet Bs is prepared in a roll shape and the length of band sheet Bs is changed according to the thickness of sheet bundle St, the number of sheets, and the like, the bound sheet bundle St can be obtained without changing the binding position of the stapler or the like. Since the band sheet Bs is cut to a necessary length each time and used, it is possible to cope with various sizes of sheets S and various thicknesses of sheet bundles St by one type of roll. If the user wants to change the width which covers the security information portion according to a security holding level, it is also possible to prepare a plurality of rolls of different widths and to selectively use them.

Since the band sheet Bs has been perforated, if it is necessary to separate the band sheet Bs and the sheet bundle St in order to browse the sheet bundle St, the separating operation can be easily executed. Since the cut ends of the band sheet Bs also remain in the sheet bundle in the state where they have been bound with the staples after the separation, a binding force of the sheet bundle St does not decrease, binding holes are not widened, and no sheets are dropped out.

Not only the binding force can be arbitrarily changed by changing a material of the band sheet Bs but also the necessary information existing under the band sheet Bs can be clearly shown by using a transparent material. For example, by forming the band sheet Bs by a transparent film or the like, the necessary information written on the front cover, back cover, or the like of the sheet bundle St can be further clearly shown to the user. Taking of the wrong sheet bundle or the like can be prevented.

As compared with the security holding process shown in Japanese Patent Application Laid-Open No. H09-071362, when the security is cancelled and the sheet bundle is browsed, a tool for removing stapling devices such as staples or the like is unnecessary and a troublesomeness and a time which are necessary upon working are saved.

As compared with the security holding process shown in Japanese Patent Application Laid-Open No. H09-165136, since the width of band sheet Bs is narrow, a confirmation or the like of a superscription of the sheet bundle St and an inspection of the problem such as a missing of the sheet or the like in the sheet bundle can be easily performed. As compared with a band sheet having the same width as that of the sheet bundle St, the band sheet Bs can be easily torn and opened.

When the sheet bundle St becomes thick, the edge portion of the band sheet Bs can be made to correctly coincide with the edge portion on the side of one side of the sheet bundle St by adjusting the length of band sheet Bs. Therefore, there is no need to change the stapling positions of the staples to the inside of the sheet bundle St by an amount corresponding to the thickness of sheet bundle St. Consequently, in the state where the sheet bundle St is opened, opening performance of the sheets is not deteriorated. There is no risk that the cylindrical paper bands are vertically pulled out and a third party casts a furtive glance at the contents of the sheet bundle St. Since an evidence that the band sheet has been torn remains, such a situation that the user overlooks a fact that the third party casts a furtive glance at the contents of the sheet bundle St is eliminated.

Consequently, the sheet processing apparatus 200 which can form the sheet bundle that contributes to the improvement of usability of the sheet bundle in the bundle state and that can be easily opened while raising the security can be provided.

By making the most of the mechanism and control of the sheet processing apparatus which has the processing tray 213, sheet bundle conveying mechanism 220, stapler main body 240, and the like and which can execute the tying process, the option function of the security holding process can be provided at low costs and at a small size and a light weight.

The sheet processing apparatus 200 has: the stapler main body 240 which staples the edge portion on the side of one side of the sheet bundle St which is formed by a plurality of sheets S; the conveying roller 230 and the like which supply the band sheet Bs which bands the sheet bundle St; and the sheet bundle conveying mechanisms 220 and the like which wind the supplied band sheet Bs around the other side on the side opposite to the one side and overlay both edges of the band sheet Bs onto the front and back surfaces on the side of one side of the sheet bundle St. The stapler main body 240 staples both of the overlaid edges of the band sheet Bs integratedly with the edge portion on the side of one side. The conveying roller 230 and the like change the length of band sheet Bs which is supplied according to the thickness of sheet bundle St.

The sheet bundle conveying mechanisms 220 and the like, serving as a winding portion, overlay the both edges of the band sheet Bs so as to coincide with the edge portion on the side of one side of the sheet bundle St. The conveying roller 230 and the like, serving as a tying member supplying portion, load and enclose the roll-shaped band material (tying material) obtained by winding the material of the band sheet Bs which is supplied in a roll shape. The cutter 235 cuts the supplied band sheet Bs from the roll-shaped band material. The control portion 160 calculates the necessary length of the band sheet Bs based on the thickness of sheet bundle St and the sheet size of sheet bundle St and allows the band material to be cut to the necessary length by using the cutter 235.

The cutter 235 also functions as a perforating processing portion which forms the perforation to the band sheet Bs. The control portion 160 allows the perforation to be formed in the specific position of the band sheet Bs by using the cutter 235. A perforation or another process which makes the cutting easy can be also preliminarily performed to the band material at a plurality of positions in the longitudinal direction.

The band sheet Bs has the width shorter than the length of one side. It is also possible to enclose a plurality of types of band materials (tying materials) having different widths and to switch the band materials according to a necessary finishing external appearance.

The stapler main body 240 staples a plurality of stapling positions of the edge portion on the side of one side of the sheet bundle St. The conveying roller 230 and the like supply the different band sheets Bs to the plurality of stapling positions in parallel.

The sheet processing apparatus 200 has the processing tray 213 and the like which form the sheet bundle St by overlaying the received sheets S. The stapler main body 240 also functions as a device for binding the formed sheet bundle St in a booklet shape. That is, the sheet processing apparatus 200 can also output the booklet-shaped sheet bundle which is not subjected to the security holding process.

The sheet processing apparatus 200 has the sheet bundle conveying mechanism which moves the sheet bundle St while setting the edge portion on the side of the other side on the side opposite to the one side to the head and positions the edge portion on the side of one side to the stapler main body 240. The sheet processing apparatus 200 and the like winds the band sheet Bs around the sheet bundle St in association with the movement of the sheet bundle St which is performed by the sheet bundle conveying mechanism and overlays the both ends of the band sheet Bs onto the front and back surfaces of the edge portion on the side of one side of the sheet bundle St.

The image forming apparatus 10 has: the sheet processing apparatus 200 and the apparatus main body 100 which forms the images onto the sheets S and discharges the sheets to the sheet processing apparatus 200.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

This application claims the benefit of Japanese Patent Application No. 2006-326353, filed Dec. 1, 2006, which is hereby incorporated by reference herein in its entirety. 

1. A sheet processing apparatus comprising: a tying member supplying portion which supplies a tying member, the tying member is wound around a sheet bundle formed by a plurality of sheets and ties the sheet bundle; a binding unit which binds the sheet bundle integratedly with the tying member wound around the sheet bundle; and a control portion which changes a length of the tying member to be supplied by the tying member supplying portion according to a thickness of the sheet bundle.
 2. An apparatus according to claim 1, further comprising a winding portion which winds the sheet bundle with the supplied tying member, wherein the winding portion overlays both edges of the tying member so as to coincide with an edge portion on the side of one side of the sheet bundle.
 3. An apparatus according to claim 1, further comprising: a cutting portion which cuts the supplied tying member from a tying material, wherein the control portion calculates a necessary length of the tying member from the thickness of the sheet bundle and a sheet size of the sheet bundle, and controls the cutting portion so as to cut the tying material to the necessary length.
 4. An apparatus according to claim 3, wherein the control portion controls the cutting portion so as to form a perforation at a specific position of the tying member.
 5. An apparatus according to claim 3, wherein a process which makes the cutting easy has previously been performed to the tying material at a plurality of positions in a longitudinal direction.
 6. An apparatus according to claim 1, wherein the tying member has a width shorter than a length of one side of the sheet bundle.
 7. An apparatus according to claim 1, wherein the tying member supplying portion encloses a plurality of types of tying materials having different widths.
 8. An apparatus according to claim 7, wherein the binding unit binds the sheet bundle at a plurality of binding positions, and the tying member supplying portion supplies different tying members according to intervals among the plurality of binding positions.
 9. An apparatus according to claim 1, further comprising a bundle forming portion which forms the sheet bundle by overlaying the received sheets, wherein the binding unit binds the sheet bundle formed by the bundle forming portion in a booklet shape.
 10. An apparatus according to claim 9, further comprising a sheet bundle conveying mechanism which moves the sheet bundle from the bundle forming portion and positions the sheet bundle for the binding unit; and a winding portion which winds the sheet bundle with the supplied tying member, wherein the winding portion winds the tying member around the sheet bundle in association with the movement of the sheet bundle which is performed by the sheet bundle conveying mechanism.
 11. An image forming apparatus comprising: an image forming portion which forms images onto a sheet; and a sheet processing apparatus which processes the image formed sheet, wherein the sheet processing apparatus has a tying member supplying portion, the tying member is wound around a sheet bundle formed by a plurality of sheets and ties the sheet bundle; a binding unit which binds the sheet bundle integratedly with the tying member wound around the sheet bundle; and a control portion which changes a length of the tying member to be supplied by the tying member supplying portion according to a thickness of the sheet bundle.
 12. An apparatus according to claim 11, further comprising a cutting portion, provided for the sheet processing apparatus, which cuts the tying member to be supplied from a tying material, wherein the control portion calculates a necessary length of the tying member based on the thickness of the sheet bundle and a sheet size of the sheet bundle, and controls the cutting portion so as to cut the tying material to the necessary length. 